Several clones of murine erythroleukemia cells with impairments in hemoglobin synthesis arising either from treatment with an inducer or from spontaneous differentiation without inducer, have been isolated. We now propose to determine whether specific impairments in the expression of the globin genes can be identified in these clones by assay techniques. In particular, utilizing a technique that we have recently developed for separating and identifying globin chains, we propose to investigate whether free alpha and beta globin chains are present in these clones, how many types of alpha and beta chains are present, whether in some cases embryonal globin chains can be expressed, and whether equal amounts of alpha and beta globins are synthesized. Using an in vitro translation assay and RNA-DNA hybridization we will determine whether nontranslatable globin mRNA is present to some extent in those clones and whether the accumulation is due to impaired processing or impaired translation. By utilizing a system in which hemin controls the expression of the beta minor globin chain but not the beta major we will determine whether the effect of hemin is exerted at the level of translation, transcription or processing of globin mRNA. Finally, we will investigate whether the alpha globin chains are polymorphic and how expression is regulated in mouse erythroleukemia cells.